Libertarianism Again

If libertarianism is correct, then Joe does nothing wrong in the following scenario:

"Hello? Oh, Fred, hi. Yes, the mailman came, and it looked like he dropped mail at your house. Oh, by the way, your son, Bobby, is bleeding to death on your front lawn, after he severed his foot under the lawnmower. Actually, I think he's dead.... What? No, I didn't. I was busy with this crossword puzzle. I know we're next-door neighbors and all, but I have no obligation to help other people. I'm free to live on my own and be selfish as long as I don't hurt anybody.... Listen, Fred, you're obviously too upset to think clearly about this, so I'm hanging up now. Bye."

And Fred does something wrong in this scenario:

Joe: "No, he's still alive, barely."
Fred: "I have remote control of my burglar alarm next door. If I press the button, the alarm will sound. It is very, very loud and will fill your house with mind-numbing noise. I suggest that you call an ambulance for my son and administer simple first aid, or I will do this."

Clearly, Fred does nothing wrong in the second scenario, and Joe does something wrong in the first. Therefore, libertarianism is false. Until libertarians prove otherwise, they must renounce libertarianism.

Now, the libertarian could say that he need provide no proof that Fred does something wrong and Joe nothing wrong, since the non-libertarian has not provided argument to the contrary. Well and good. Carry the banner of standing idly by as a kid bleeds to death in front of you. Write on the banner "Individual liberty!" People will continue to take your position as seriously as they do now. You simply do not share American values. You want us to accept new values, just like the far left does. But as long as the vast majority in America share a coherent set of non-libertarian values that they prefer and that is consistent with the relevant facts, it is logically impossible for the libertarian to get a wedge underneath those values and overturn them. It is rational for us to live by our values, as long as they are coherent and informed. So, you want us to accept new values, but you have no evidence that we should accept them. Therefore, libertarianism, like far leftism, is a fanaticism.

UPDATE: To be clear: This is an argument for a minimal welfare net funded by taxation. In addition, I have many libertarian friends. They aren't fanatics, and I apologize for calling them that. They are excellent members of the community of inquirers, whom we are lucky to have around. I let some other libertarians, who are fanatics, led me to lose my cool. I'm sorry.